1. Animal Behaviour, Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse, Zurich, Switzerland
2. Centre for Evolutionary Biology, School of Animal Biology, The University of Western Australia, Stirling Highway, Crawley, Australia
3. Percy FitzPatrick Institute, University of Cape Town, University Avenue, Rondebosch, South Africa
4. Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool, UK
5. Department of Psychology, University of Warwick, University Road, Coventry, UK
6. Comparative Communication and Cognition Group, Department of Comparative Linguistics, University of Zurich, Plattenstrasse, Zurich, Switzerland